intensified eu(iii)extraction using ionic liquids in...

1

Intensified Eu(III)extraction using ionic liquids in small channels

Qi Li Panagiota Angeli

Department of Chemical Engineering University College London Torrington Place London WC1E 7JE UK

Corresponding author Tel ++44 (0) 20 7679 3832 Fax ++44 (0)20 7383 2348 Email pangeliuclacuk

Abstract

The extraction of Eu(III) from nitric acid solutions was studied in intensified small scale separation units

using an ionic liquid solution (02M n-octyl(phenyl)-NN-diisobutylcarbamoylmethyphosphine oxide

(CMPO) -12M Tributylphosphate) (TBP)1-butyl-3-methylimidazolium

bis[(trifluoromethyl)sulfonyl]amide ([C4min][NTf2])as the extraction phase The investigations were

carried out in channels with 02 mm and 05 mm diameter for phase flowrates that result in plug flow

with the aqueous solution as the dispersed phase The interfacial area in plug flow and the velocity

profiles within the plugs were studied with high speed imaging and bright field micro Particle Image

Velocimetry Distribution and mass transfer coefficients were found to have maximum values at nitric

acid concentration of 1M Mass transfer coefficients were higher in the small channel where

recirculation within the plugs and interfacial area are large compared to the large channel for the same

mixture velocities and phase flow rates Within the same channel mass transfer coefficients decreased

with increasing residence time indicating that significant mass transfer takes place at the channel inlet

where the two phases come into contact The experimental results were compared with previous

correlations on mass transfer coefficients in plug flows

1 Introduction

Within the frame of process intensification the miniaturization of chemical operations opens up new

possibilities in separations Microchemical systems with well-defined channel structures in the range of

a few hundred μm are characterised by thin fluid layers and large surface-to-volume ratios which

improve heat and mass transfer rates and coupled with narrow residence time distributions result in

better process efficiency and control (Loumlwe and Ehrfeld 1999 Kiwi-Minsker and Renken 2005) The

increased importance of interfacial phenomena large interfacial areas and the ability to influence flow

patterns make two-phase flows in small units particularly appealing The benefits of microchannel

operation have been clearly demonstrated for liquid-liquid extractions which often involve organic

solvents with high hazard ratings (Kashid et al 2005 Dessimoz et al 2008 Kashid et al 2010

2

Assmann et al 2013 Xu et al 2013 Yang et al 2013)As extraction efficiencies depend on

concentration gradients interfacial area and residence times (Okubo et al 2008) the exact flow pattern

within the separation unit becomes important Plug (or segmented) flow in particular where one phase

forms dispersed plugs with diameter larger than the channel size separated by continuous phase slugs is a

preferred pattern because the circulation patterns forming in the two phases and the thin films separating

the plugs from the channel wall enhance mass transfer (Burns and Ramshaw 2001 Kashid et al 2005

Okubo et al 2008 Jovanović et al 2012) In addition the dispersed plug sizes are very regular and can

be controlled via the choice of the inlet geometry which further reduces non-uniformities common in

large scale extraction units such as mixers-settlers(Khakpay et al 2009) Knowledge of the interfacial

area is very important in the understanding and modelling of extraction operations Chemical reactions

eg alkaline hydrolysis of esters have been used to obtain global values of interfacial area in units such

as agitated contactors(Fernandes and Sharma 1967) packed columns(Puranik and Sharma 1970 Verma

and Sharma 1975)and two-impinging-stream reactors(Dehkordi 2002)In small channels where flow

patterns are well defined high speed imaging can be used to acquire details of the flow pattern locally

such as film thickness and plug length and estimate the interfacial area (Ghaini et al 2010 Xu et al

2013)

One of the separations that can benefit from operation in small channels is the extraction of lanthanides

from acidic solutions Lanthanides with their strong photoluminescence and magnetic properties are

important to many industrial applications Europium and yttrium oxides can be used as fluorescing agents

for anodic rays in television and monitor screens (Lee and Yang 1995) Lanthanide oxides are used to

colour ceramics and glasses (Goonan 2011) Some compounds of lanthanides find applications as

catalysts for example oxides of thorium and cerium are used in the conversion of crude oil into common

consumer products (Lew 2010) Lanthanides have also been used to regulate nuclear reactors as control

rods because they absorb neutrons (Kučera et al 2007) and to make strong permanent magnets (Wang et

al 2011) Scarcity on natural resources means that the large quantities of lanthanides present in

electronic waste such as spent fluorescent lamps (Rabah 2008) computer monitor scraps (Resende and

Morais 2010) and colour TV tubes (De Morais 2000) need to be recycled In the field of spent nuclear

fuel reprocessing recovery of the trivalent actinides and lanthanides is a key step in high-level waste

management Since trivalent lanthanides cannot be extracted by TBP they are rejected to high-level

liquid waste in the PUREX process (Rout et al 2011a) They can however be extracted by the TRUEX

solvent which is a mixture of 02 M CMOP- 12 M TBP in n-dodecane (Horwitz et al 1982 Schulz and

Horwitz 1986)

3

Further intensification of the extraction process can be achieved by using room temperature ionic liquids

(RTILs or ILs) which have emerged as alternatives to organic solvents for catalytic reactions and

separations Ionic liquids are salts with very low vapour pressure that can dissolve a wide range of

organic and inorganic compounds It has been found that when ILs are used in extractions as diluents in

conjunction with appropriate extractants the partition coefficients for lanthanides are increased compared

to conventional solvents(Chun et al 2001 Okamura et al 2012 Rout et al 2012) The distribution ratio

of Eu(III) in CMPO-TBP[C4min][NTf2] can be 10 times larger than when n-dodecane (n-DD)is

used(Rout et al 2011a) Nakashima et al (2003)studied the extraction behaviour of trivalent lanthanides

in the presence of CMPOC4mimPF6 and found that use of ILs as the diluent of the extracting phase can

reduce extractant consumption compared to a conventional solvent (n-DD) However the industrial use

of ionic liquidsis still limited because of their high production costs This barrier can be overcome with

the use of the small scale separators which intensify mass transfer and can lead to the reduction of the

amount of solvent required

In this work the continuous extraction of Eu from nitric acid solutions is studied for the first time in

microchannels using an ionic liquid solution (02M CMPO-12M TBP[C4mim][NTf2]) as the extraction

phase In what follows the experimental set up and methodology are presented and the high speed

imaging and bright field Particle Image Velocimetry (PIV) techniques that are used to study the

hydrodynamic characteristics of the plug flow are discussed Results are then shown on europium

extraction efficiencies and mass transfer coefficients and are related to the geometric parameters of the

plug flow and the circulation patterns inside the plugs The mass transfer coefficients are also compared

against literature correlations and values from conventional large scale systems

2 Materials and experimental methodologies

In this study the continuous extraction of Eu(III) from nitric acid solutions to a

CMPOTBP[C4mim][NTf2] solution was carried out in 02 mm and 05 mm ID capillary channels The

ionic liquid [C4min][NTf2] with viscosity of 0052 Pa∙s and density of 1420 kg∙m-3 was obtained from

the QUILL Research Centre Queenrsquos University of Belfast The tri-n-butylphosphate (TBP) which acts

as a modifier to prevent the formation of lsquocrud-typersquo precipitate (Rout et al 2011b) was purchased from

Sigma-Aldrich CMPO was used as extractant and obtained from Carbosynth Limited For the

preparation of the ionic liquid phase certain amount of CMPO was added into TBP and the mixture was

mechanically shaken for 2 hours Then the mixture was introduced into the ionic liquid [C4min][NTf2]and

stirred The concentrations of CMPO and TBP in the ionic liquid were equal to 02M and 12 M

respectively Various standard nitric acid solutions were obtained from Sigma-Aldrich and used as

4

aqueous phase The ionic liquid was pre-equilibrated with the desired concentration of nitric acid solution

before extraction because both H+ and NO3-can dissolve in the IL phase The solubility of H+ and NO3-

into the ionic liquid follows a physical absorption than a chemical extraction mechanism(Billard et al

2011b) and neither TBP nor CMPO influence it The fluid properties of the ionic liquid (02M

CMPO-12M TBP[C4min][NTf2]) and aqueous solutions (1M nitric acid) are summarized in Table 1

(measured at UCL laboratory) Each measurement was repeated 3 times to ensure reproducibility The

liquid viscosity and density were measured with a digital DV-III Ultra Rheometer (Brookfield UK) and a

DMA 5000 density meter (Anton Paar UK) respectively The interfacial tension was measured using a

DSA 100 drop analyzer (Kruss GmbH Germany) The refractive index was measured with an Abbe 5

Refractometer (Bellingham and Stanley UK) The diffusion coefficient of Eu(III) in the aqueous and

ionic liquid phases was obtained from the literature(Matsumiya et al 2008 Rao et al 2009 Ribeiro et

al 2011 Sengupta et al 2012 Yang et al 2014)

21 Experimental apparatus

A sketch of the experimental set up is shown in Fig1 Two Kds Legato syringe pumps (KD Science Inc

USA) were used to feed the two liquid mixtures to a T-junction with an error of 1 The aqueous phase

was injected perpendicular to the channel axis and the ionic liquid phase was introduced at the axis of the

main channel A sketch of circular 02 mm ID microchip made of Quartz from top view is shown in Fig 2

The main channel length (CL) for the 05 mm ID capillary varied from 5 to 25 cm The different lengths

were used to vary the residence time in the extractor without changing the mixture velocity which can

affect the flow pattern Both phases were introduced at the same volumetric flow rate which varied from

Qaq=QIL=0653 to 21205 mlhr Plug flow formed in all cases studied with the aqueous solution forming

always the dispersed plugs and the ionic liquid the continuous phase At the channel exit a flow splitter

with a PTFE channel as the main branch and a stainless steel channel as the side branch was used to

separate the two phases continuously (for details see Scheiff et al (2011) Tsaoulidis et al (2013)) An

Asia FLLEX module (Syrris Ltd UK) was also used as a continuous phase separator operated by

adjusting the pressure differential across a hydrophobic PTFE membrane This separator could not be

used at high flow rates though because of high pressure drops The separated phases were analyzed for

Eu(III) concentration in a USB2000+ UV-Vis spectrometer (Ocean Optics UK) After each set of

experiments the microchannel was cleaned with dichloromethane to remove any residual ionic liquid

then with acetone to remove any dichloromethane left At last compressed air was injected to the channel

to ensure that all the chemicals have been cleaned All experiments were conducted under ambient

temperature (238-255degC)

5

High speed imaging was used to study the hydrodynamic characteristics of the two phase system (Fig 1)

A 60-Watt continuous arc lamp was used to volumetrically illuminate the microchannel from the back

and a diffuser plane was added between the backlight and the test section for uniform illumination To

minimize optical distortions an acrylic box filled with water was put around the channel Because of the

background illumination the interface appears as a shadow which is captured by a high speed camera

(Photron Fastcam-Ultima APX UK) with adjustable image recording frequency from 2000 to 8000Hz

depending on flowrates The camera was coupled with an air-immersion long working distance objective

lens with magnification M=3 to 10 depending on the channel dimension In addition a bright field

Particle Image Velocimetry technique was applied with the same optical set up to obtain the velocity

profiles within the aqueous plugs For the velocity measurements the aqueous phase was seeded with

3μm polystyrene particles and their shadow was recorded by the high speed camera (resolution

1024X1024 pix2) The Insight 4G (TSI instrument) software was used to pre-process and capture the

images while data analysis was carried out with an in-house MATLAB code A median filter was applied

to the images to eliminate any background noise The displacement of tracer particles between two

consecutive frames was calculated to obtain velocity vectors using a square domain discretization of 32 X

32 pixels with 50 overlap to satisfy the Nyquist sampling criterion(Dore et al 2012) with velocity

spatial resolution of 2672 μm times 2672 μm in the 05 mm channel The correlation peak position was

computed with Gaussian peak algorithm detection and the validation of the velocity vectors was based on

standard deviation and primary to secondary peak vectors Removed false vectors were replaced with the

median value of neighboring velocity vectors (Chinaud et al 2015)

22 Chemical mechanisms

The chemical structure of [C4min][NTf2] ionic liquid is shown in Fig3 The stoichiometry of

metal-solvate in the ionic liquid phase varies from 13 (Eu CMPO) at trace levels to 11 at higher Eu(III)

loadings It is determined by the slope analysis of logDEu against log[CMPO]org(Rout et al 2011b)

where species with overline exist in the ionic liquid phase only

Eu3+ + xCMPO + 3NO3minus harr Eu(NO3)3 ∙ (CMPO)x

(1)

However the equilibrium often involves ion exchange between the aqueous and the ionic liquid phases

Billard et al (2011a) found that the cation part of the ionic liquid C4mim+ was present into the aqueous

phase after extraction By dissolving C4mimCl into the aqueous phase it was shown that the presence of

C4mim+ reduced the extraction efficiency (Nakashima et al 2005) In some cases anion exchange was

also observed for example Tf2N- transferred to aqueous Htta solution when Eu(III) was extracted from

ionic liquid (Okamura et al 2012) However there is no clear evidence of anion exchange when ionic

liquid acts as diluent because Tf2N- is a weakly coordinating anion (Binnemans 2007) According to the

6

above the mechanism can be written as

Eu3+ + xCMPO + 3NO3minus + 3C4mim+ harr Eu(NO3)3 ∙ (CMPO)x

+ 3C4mim+ (2)

When ILs are used to recover Eu(III) in conjunction with neutral extractants the reaction takes place in

the ionic liquid phase and not in the aqueous phase as it happens with conventional solvents Very limited

research is available on the extraction kinetics of Eu(III) coupled with ionic liquid The separations of

certain rare earth metals are characterized by fast reaction but slow mass transfer using conventional

organic solutions (Sarkar et al 1980) When ionic liquids are used however this may not be the case

due to their unique ion exchange mechanisms Brigham (2013) investigated lanthanide extraction by

HDEHP in n-dodecane from DTPA and found that the reaction follows pseudo first- or second-order

kinetics The second order rate constant of Eu(III) extraction was about 104 M-1s-1 which falls into the

range of fast reactions (1 to 1010 M-1s-1(Caldin 2001)) Therefore the present extraction system was

treated as fast reaction although further research is still needed to accurately describe it

3 Results and Discussion

31 Specific interfacial area

The rate of mass transfer between two phases depends on the interfacial area available For the

calculation of the interfacial area in plug flow it is assumed that the dispersed plugs have a cylindrical

body and hemispherical caps at the front and back When a continuous film is a present at the channel

wall the interfacial area can be calculated as follows with an error of less than 10(Raimondi et al

2014)

120572119901 =4119882119901(119871119875minus119908119901)+120587119882119901

2

1198711198801198621198681198632 (3)

where Luc is the unit cell length (one slug and one plug) and Wp and Lp represent the plug width and

length respectively The plug geometric parameters for each set of flow rates were obtained by averaging

results from 30 plugs with deviations between 425-710for film thickness and 533-952 for plug

and unit cell length

The effect of mixture velocity on interfacial area can be seen in Fig4 for equal flow rates of the two

phases from Qaq=QIL=3534 to 2121 mlh The interfacial area was found to increase slightly with

increasing Umix As the mixture velocity increases the plug formation frequency increases while shorter

plugs form which results in larger interfacial area values However the capillary diameter has a more

profound effect the interfacial area in the large channel is almost 3 times smaller than in the small one

7

for the same mixture velocity It has been suggested that the organic film can be ignored during mass

transfer at low mixture velocities (Ghaini et al 2010) However when ionic liquid is the continuous

phase the film (δfilmR = 01585-03022 where δfilm and R are film thickness and channel radius

respectively) is thicker than with conventional organic solvents (δfilm R = 00928-01295) and may affect

mass transfer

32 Distribution coefficients for Eu(III) extraction

To characterize the mass transfer process a number of parameters will be used The Eu(III) distribution

coefficient DEu is defined as the ratio of concentration of europium in the ionic liquid phase to the

concentration in the aqueous phase

119863119864119906 =119862119886119902119894119899119894minus119862119886119902

119890

119862119886119902119890 (4)

The Eu(III) distribution coefficients for the aqueous-ionic liquid system were measured at different nitric

acid concentrations (001 01 05 10 and 20M) In the experiments equal volumes of nitric acid

solution containing europium nitrate and of ionic liquid solution (02M CMPO-12M TBP[C4min][NTf2])

were mechanically shaken for 3 hours The initial loading of Eu(III) in the aqueous phase was 20 30 and

50 mgmL respectively After equilibrium the Eu(III) concentration was measured in the aqueous phase

in a UV-Vis spectrometer Fig5 illustrates the Eu(III) distribution coefficient (DEu) as a function of initial

nitric acid concentration (Caqini) Each equilibrium experiment was repeated 5 times The relative

deviation was quite large for the low Eu(III) loading (20mgmL) ranging between 369 and 2876

but decreased to 255 - 1418 at 50 mgmL loading where the absorption signal in the UV-Vis is

stronger and more stable than at lower loadings The Eu(III) concentration in the ionic liquid phase was

also measured with UV-Vis The amount after extraction was between 8965 to 10154 of the initial

Eu(III) loading It would be difficult to have better agreement because the IL cations the NO3-or the

impurities in the imidazolium-based ionic liquids also have absorption characteristics in the UV range

that can mask the Eu(III) signal (Billard et al 2011a)

As can be seen from Fig5 the distribution coefficient reduces with increasing Eu(III) loading which

means that the Eu(III) in the aqueous phase is more difficult to be distributed into the ionic liquid phase

However 50 mgmL concentration was chosen for the microchannel extraction experiments because of

the low concentration measurement errors Furthermore the distribution coefficient has its highest value

at 10M nitric acid concentration for all initial Eu(III) loadings which is in agreement with the results by

Rout et al (2011b) The distribution coefficients obtained when ionic liquid is used are by a factor of 10

higher to those achieved with the conventional TUREX solvent (02M CMPO-12M TBPn-DD) (Rout et

8

al 2011a)

33 Mass transfer in continuous extraction

The performance of a mass transfer unit is characterized by the mass transfer coefficient (KLa) The

driving force for mass transfer will vary along the length of the microchannel and a log mean

concentration difference (LMCD) can be used defined as

∆119871119872119862119863=(119862119886119902119894119899119894

119890 minus 119862119886119902119894119899119894) minus (119862119886119902119891119894119899119890 minus 119862119886119902119891119894119899)

ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)

The mean value of the mass transfer flux can be written as

119873 = 119870119871∆119871119872119862119863 (6)

The mean value of the mass transfer flux is also equal to

=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)

By combining Eqn (6) and Eqn (7) and integrating from the initial (119862119886119902119894119899119894) to the final concentration

(119862119886119902119891119894119899) for time between 0 and the residence time τ the overall mass transfer coefficient is found

119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)

The extraction efficiency Eeff refers to the ratio of the amount of species transferred to the maximum

amount transferable

119864119890119891119891 =Amount transferred

Maximum amount transferable=

119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)

The efficiency is a good indicator of the mass transfer performance of the contactor at various contact

times (Bapat and Tavlarides 1985 Dehkordi 2001) The extraction efficiency depends not only on the

overall volumetric mass transfer coefficient (KLa ) but also on the residence time (τ)

The overall volumetric mass transfer coefficients of the Eu(III) extraction in the 05 mm ID microchannel

calculated from Eqn (8) are shown in Fig6a as a function of residence time To obtain different

residence times (τ) the channel length was varied from 5 cm 15 cm to 25 cm at the same volumetric

flow rates of the two liquids Qaq= QIL=3534 mlhr The volumetric mass transfer coefficient was found to

decrease non-linearly with increasing residence time On average the mass transfer coefficient of τ=10s

(CL=5 cm) was 15 times higher than that of τ=30 s (CL=15 cm) under all nitric acid solutions while the

change between τ=30 s and τ=50 s (CL=25 cm) was small This suggests that the mass transfer at the inlet

of the channel contributes significantly to the overall mass transfer in the separation unit The nitric acid

9

concentration affects the mass transfer coefficient in a similar way that it affects the distribution

coefficient (Fig 5) The highest mass transfer was found at 10M nitric acid concentration followed by

the 05 and 20 M concentrations The lowest KLa were found for 01M nitric acid concentration

The effect of residence time on extraction efficiency can be seen in Fig6b In all cases the extraction

efficiency increases with residence time In the shortest channel (CL=5 cm and τ=10 s) the extraction

efficiency is relatively low (4355) despite the high mass transfer coefficients The highest Eeff was

found at 1M nitric acid concentration and at the longest residence time where it reaches 7150 of the

equilibrium value

34 Effect of mixture velocity on Eu(III) microfluidic extraction

The effect of mixture velocity on overall volumetric mass transfer coefficient was investigated in the

05mm ID microchannel (CL=15 cm) at varying nitric acid concentrations for equal volumetric flow

rates of the two phases ranging from Qaq=QIL=3534 to 2121 mlhr As can be seen in Fig7 for 1M nitric

acid concentration the mass transfer coefficient increases with increasing mixture velocity which means

the extraction system is mass transfer dominated The increase in the mass transfer coefficient is partly

attributed to the small increase in interfacial area (see Fig4) This contribution however is small for

example the area increases by 464 when the mass transfer coefficient rises by 54 for change in

velocity from 05 to 3 cms Mixture velocity affects mass transfer in plug flow via two mechanisms(a)

convection due to internal circulation in the plugs and slugs (b) molecular diffusion due to concentration

gradients adjacent to the interface (Kashid et al 2007 Dessimoz et al 2008) The increase in mixture

velocity increases the intensity of internal circulation and enhances convective mass transfer (Tsaoulidis

and Angeli 2015) The circulation also helps interface renewal that increases the concentration gradients

and therefore mass transfer close to the interface The mass transfer performance however does not

depend only on mixture velocity and as can be seen at nitric acid concentration different from 1M the

effect of mixture velocity on the mass transfer coefficient is less significant The extraction of Eu(III) is a

physical process combined with chemical reaction and depends on both mass transfer and intrinsic

reaction kinetics (Xu et al 2013)

To evaluate the role of film thickness on mass transfer van Baten and Krishna (2004) proposed different

correlations for mass transfer from the plug caps and the film in the plug flow regime

119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )

(1minus∆) Folt 01 (short contact) (11)

10

119870119871119891119894119897119898 = 341119863

120575119891119894119897119898 Fogt 01 (long contact) (12)

119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)

where the Fourier number (Fo) is defined as Fo=Dtfilm δfilm2 and ∆ is a dimensionless parameter based on

Fo The plug velocity Up is obtained based on the plug displacement from the high speed imaging The

contact time of the liquid film tfilm =Lfilm (Up + Ufilm) is calculated under the assumption that the film

velocity is nearly negligible in the microchannel The mass transfer via the film can be evaluated

depending on the value of the Fourier number (Fo) where Folt 01 and Fogt 01 for short and long

contact time respectively The aqueous plug in the present work shows long film contact times as Fo

ranges between 0486 and 1235 The Eu(III) KLfilm in the 02 mm ID channel was found to decrease from

4702 to 3353 times 10-7 ms-1 when Umix increased from 001 to 006 ms and KLcap increased from 1151 to

2985 times 10-5 ms-1 under the same operation conditions These results show that 99 Eu(III) is extracted

via the cap regions and the film region has a minor effect on the overall mass transfer It explains why

high KLa occurs at larger Umix where plug formation frequency increases and shorter plugs form which

would result in increased cap regions that enhance mass transfer At Umixgt004 ms where Fogt08 and

Δasymp0 (van Baten and Krishna (2004)) the ionic liquid film approaches saturation and its contribution to

the overall mass transfer becomes insignificant

The Eu(III) extraction efficiency is shown in Fig 8 for the 05 mm ID microchannel (CL=15 cm) The

extraction efficiency increases with increasing residence time (decreasing mixture velocity) The highest

extraction efficiencies are obtained for 1M nitric acid concentration similar to distribution coefficients

(see Fig 5) Although the mass transfer coefficient at Umix=3 cms has the highest values the

corresponding extraction efficiencies are only 3624 to 5813 of the equilibrium value due to the short

residence times (τ=5s)

35 Effect of capillary size on Eu(III) extraction

The effect of channel size on overall volumetric mass transfer coefficient is shown in Fig9 for 02 and

05 mm ID capillaries as a function of mixture velocity at the same channel length (CL=25 cm) 1M nitric

acid was used as aqueous phase and equal flow rates of the both phases were used varying from 0065 to

1414mlh Generally KLa are higher in the small channel because of the large interfacial area compared

to the 05 mm channel As depicted in Fig4 the average interfacial area increases from 3600 m2m3 to

8250 m2m3 when the capillary internal diameter reduces from 05mm to 02mm The difference between

the mass transfer coefficients increases with mixture velocity For example at Umix=1 cms the difference

is about 105 of the 05 mm channel KLa but increases to 214 at Umix=3 cms The increased surface

11

renewal rate and recirculation intensity caused by higher plug velocities in the small channel are

considered to be responsible for the difference In fact the plug velocity is always higher than the

mixture velocity in the liquid-liquid plug flow regime due to the existence of a nearly stagnant ionic film

surrounding the aqueous phase plug The non-dimensional film thickness (δfilmR) in the 02 mm ID

channel was found to be 847-3292 larger than in the 05 mm ID channel from the imaging

experiments depending on the mixture velocity Therefore the enclosed plug moves slightly faster in the

small channel This is also confirmed by the imaging experiments which showed that plugs in the 02

mm ID channel moved594- 1774 faster compared to the large channel

36 Effect of recirculation intensity on Eu(III) microfluidic extraction

The convective mass transfer inside the plugs is strongly affected by the recirculation patterns which are

caused by the shear between the continuous phase and the plug axis To obtain the recirculation patterns

for each set of conditions the instantaneous velocity profiles of 30 plugs were averaged with a deviation

of 435-999 The average plug velocity was then calculated by integrating the laminar velocity profiles

of the averaged velocity field along the plug length The recirculation pattern was finally obtained by

subtracting the average velocity from the local velocities in the plug An example of the averaged

recirculation pattern inside a plug is shown in Fig 10afor Qaq=QIL=3534 mlhr It consists of two counter

rotating vortices with closed streamlines and symmetrical about the channel axis The recirculation

intensity within the plug is characterized by the recirculation time which is the time needed to displace

material from one to the other end of the plug (Thulasidas et al 1997 Kececi et al 2009 Dore et al

2012) A two-dimensional recirculation time was calculated as follows (Dore et al 2012)

τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)

where yo is the location of the stagnation point projected onto the observation mid-plane As can be seen

from Fig 10b the recirculation time is almost constant in the middle of the channel but increase towards

the front and back ends of the plug where the streamlines are not well defined The recirculation time is

usually treated as constant inside the liquid plug(Thulasidas et al 1997 Kashid et al 2005 Tsoligkas et

al 2007) However Dore et al (2012)experimentally found that the circulation pattern may not be fully

symmetric especially at shorter plugs

The recirculation times averaged for the middle part of the plug are plotted in Fig 11 against the plug

travel time in the 05mm ID channel for Qaq=QIL=3534 to 2121 mlhr The plug travel time is defined as

the time needed by the liquid plug to travel a distance of its own length given by Tp=LpUmix where Lp is

the plug length The corresponding mass transfer coefficients are also plotted As discussed above high

12

mixture velocities (Umix) result in shorter plug lengths thus leading to a shorter plug travel time (Tp) In

shorter plugs decreased recirculation times are observed which means the fluid in the plug will

experience a larger number of revolutions and better mixing This is supported by the increase in the

mass transfer coefficient at low Tp where the circulation time is also short A similar trend was also

observed by Kashid et al (2005)who argued that high mixture velocities increase recirculation intensity

because of increased shear between the wall surface and the plug Meanwhile higher mixture velocity

increases the thickness of the film surrounding the plug and decreases the plug diameter which results in

a shorter path length for the Eu(III) diffusion in the radial direction that also helps mass transfer

37 Comparison of KLa with correlations

Mass transfer in multiphase small scale units is a complex process which depends not only on the

hydrodynamic characteristics but also on the kinetics of the species transfer Several models have been

proposed to estimate mass transfer coefficients in gas-liquid and liquid-liquid plug flow either empirical

or developed from the film and penetration theories Bercic and Pintar (1997) suggested a correlation

Eqn(15) for gas-liquid flow which considers only the contribution of the plug caps since as the authors

argued the film becomes quickly saturated This model was able to predict accurately 119896119871120572for long

bubbles and liquid slugs Vandu et al (2005) suggested a model for the mass transfer coefficient where

the dominant contribution was from the film (Eqn 16) A constant was introduced whose value was

estimated from the best fitting of experimental data from different unit cell lengths LUC gas hold up εG

and rise velocity Up Yue et al (2009) proposed an empirical correlation (Eqn 17) suitable for short films

and non-uniform concentration in the plugs which differs from the well mixed assumption of the

previous models Similarly Kashid et al (2010) developed an empirical correlation (Eqn 18) specifically

for liquid-liquid plug flow as a function of Reynolds number Capillary number diameter and length of

the capillary The correlation was able to predict the experimental data within 95 even when the density

viscosity and interfacial tension of the aqueous phase was changed with the addition of surfactants

The mass transfer coefficients measured in 02 and 05mm ID channels are compared with these

correlations in Fig12The fitting parameters in the correlations byVandu et al (2005) (Eqn16) Yue et al

(2009)(Eqn 17) and Kashid et al (2010) (Eqn 18) were determined from least square regression analysis

of the data in both channels

119896119871120572 = 0111(119880119901+119880119904)

119

((1minus 119866)119871119880119862)057 (15 Bercic and Pintar 1997)

119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

(18 Kashid et al 2010)

The model suggested by Bercic and Pintar (1997) shows deviations as high as 5541 compared to the

experiment results This correlation does not include the effect of channel size and it was developed for

velocities higher than those used in this work Besides the liquid slug length (3-135 cm) and unit cell

length (17-22 cm) considered for the model development were about 100 times larger than in the current

work The model byVandu et al (2005)gives better predictions particularly for the large channel with

standard deviation varying from 1153 to 4212 The correlation was in fact developed for gas-liquid

flow in 1-3 mm ID capillaries for bubbles and liquid slugs longer (LUC=5 ndash 60 mm) than in the present

work (LUC=0314-1153 mm) The predictions of the two empirical correlations (Eqn 17 and 18) are

better with deviations less than 20 The model by Yue et al (2009) (standard deviation 535-1672)

was developed based on the physical absorption of oxygen from rising air bubbles into water in square

microchannels with ID=04 mm The differences from the current data may be attributed to the low mass

transfer resistance in the gas phase bubbles compared to liquid plugs The model by Kashid et al (2010)

which was developed from liquid-liquid systems agrees best with the experiment results (standard

deviations 516 -1188) Empirical correlations may agree better with the experimental data because the

effects of chemical reaction kinetics and inlet junction configuration can be included in the constants

while such effects are not taken into account in the models based on film and penetration theory on a

fully formed plug (Eqn15 and Eqn16)

Preliminary Eu(III) extraction experiments were carried out with cyclohexane as organic phase diluent

for comparison in the 05 mm ID channel The Eu(III) was extracted with 50 TBP in cyclohexane from

2 M nitric acid and the distribution coefficient was found to be between 0024 and 0041 Under the same

flow rate of both phases the KLa of the cyclohexane system (00262-00643s-1) was similar to that of the

ionic liquid system (00339-00602s-1) However the Eu(III) initial loading when cyclohexane was used

was only 031 mgmL (2times10-3 M) because of the low limiting organic concentration (LOC) In

conventional systems like n-DD or cyclohexane as organic diluent the LOC of europium is 9 mgmL

beyond this concentration the organic phase will split into two phases a heavier (rich in metal-solvate)

and a lighter phase (rich in diluent) called third phase formation This is not observed when the ionic

liquid is used even when the loading of Eu(III) in the ionic liquid phase increased from 12 to 40 mgmL

(Rout et al 2011a) Therefore the high process capacity is an additional benefit of the present system

The mass transfer coefficients and interfacial areas found in this work are compared against those from

other microfluidic units and conventional extract ion units in Table 2 For the comparisons of KLa values

in microfluidic system previous studies using different liquid-liquid extraction systems are listed as well

14

As can be seen the interfacial areas are comparable to those obtained in other microfluidic systems but

significantly higher than those in conventional extraction units The mass transfer coefficients are again

higher than the ones achieved in conventional extractors but not as high as those in different microfluidic

applications This may be due to the low distribution coefficients found for the Eu(III) extraction

4 Conclusions

The intensified extraction of Eu from nitric acid solutions into an ionic liquid phase 02M CMPO-12M

TBP[C4mim][NTf2] was studied experimentally in small channels with diameters 02 and 05 mm

Experiments were carried out in the plug flow regime where the aqueous solution formed the dispersed

plugs and the ionic liquid solution was the continuous phase Phase equilibrium studies showed that the

distribution coefficients had the highest value at nitric acid concentration equal to 1M The geometric

characteristics of the flow pattern (plug length film thickness and interfacial area) were investigated with

high speed imaging while velocity fields within the aqueous phase plugs were obtained using high speed

bright field micro PIV

The results revealed that the interfacial areas and the mass transfer coefficients were significantly higher

than in conventional contactors In addition KLa were found to be higher in the small channel compared

to the large one for the same mixture velocities as a result of large interfacial areas and reduced

circulation times Within the same channel the mass transfer coefficients increased and then decreased

with increasing nitric acid concentration in accordance with the partition coefficients The mass transfer

coefficients were also found to decrease with residence time suggesting that significant mass transfer

occurs at the channel inlet The mixture velocity affected the mass transfer coefficient particularly in the

case of 1M nitric acid concentration The circulation times within the plugs calculated from the detailed

velocity profiles were found to decrease with decreasing plug size and increasing mixture velocity small

circulation times result in better mixing and mass transfer The empirical correlation suggested by Kashid

et al (2010) was able to predict the current results (with deviations 516-1188) better than other

literature correlations

Nomenclature

Latin Symbols

Ca Capillary number Ca=120583119868119871119880119898119894119909

120574 dimensionless

Caqini initial concentration of Eu(III) in aqueous phase molL-1

15

Caqfin final concentration of Eu(III) in aqueous phase molL-1

119862119886119902119890 Eu(III) concentration in aqueous phase at equilibrium molL-1

C(HNO3) nitric acid concentration M

CL channel length cm

D Eu(III) diffusion coefficient m2 s-1

DEu Eu(III) distribution coefficient

Eeff extraction efficiency

KL overall mass transfer coefficient ms-1

KLa overall volumetric mass transfer coefficient s-1

KLcap mass transfer via cap s-1

KLfilm mass transfer via film s-1

Lfilm film length m

119871119875 plug length m

Ls slug length m

119871119880119862 length of unit cell m

n Refractive index dimenionless

N mass transfer flux mol m-2s-1

Qaq volumetric flow rate of aqueous phase mlh-1

QIL volumetric flow rate of ionic liquid phase mlh-1

ID channel internal diameter mm

R channel internal radius mm

Re Reynolds number Re=

120588119880119898119894119909119868119863


tfilm Contact ime of liquid film s

Umix mixture velocity cms-1

Up plug velocity cms-1

Ufilm film velocity cms-1

119882119901 plug width m

Greek Symbols

120572119901 plug interfacial area m2m-3

ρ density kgm-3

τ residence time s

δfilm film thickness mm

μ dynamic viscosity cp

γ Interfacial tension mNm-1

∆ dimensionless parameter

∆119871119872119862119863 log mean concentration difference molm-3

16

Acknowledgements

Financial support from the UCL Engineering Faculty and China Scholarship Council are gratefully

acknowledged The authors would like to thank Prof Kenneth R Seddon and Dr Natalia V Plechkova of

Queenrsquos University Ionic Liquids Laboratories (QUILL) for providing the ionic liquids and the UK

Engineering and Physical Sciences Research Council (EPSRC) for the loan of the Photron Ultima APX

high-speed camera

References

Alper E 1988 Effective interfacial area in the RTL extractor from rates of extraction with chemical reaction

Chemical engineering research amp design 66 147-151

Assmann N Ładosz A Rudolf von Rohr P 2013 Continuous Micro Liquid-Liquid Extraction Chemical

Engineering amp Technology 36 921-936

Bapat P Tavlarides L 1985 Mass transfer in a liquid-liquid CFSTR AIChE Journal 31 659-666

Bercic G Pintar A 1997 The role of gas bubbles and liquid slug lengths on mass transport in the Taylor

flow through capillaries Chemical Engineering Science 52 3709-3719

Billard I Ouadi A Gaillard C 2011a Liquidndashliquid extraction of actinides lanthanides and fission

products by use of ionic liquids from discovery to understanding Anal Bioanal Chem 400 1555-1566

Billard I Ouadi A Jobin E Champion J Gaillard C Georg S 2011b Understanding the Extraction

Mechanism in Ionic Liquids UO22+HNO3TBPC4-mimTf2N as a Case Study Solvent Extraction and Ion

Exchange 29 577-601

Binnemans K 2007 Lanthanides and actinides in ionic liquids Chemical reviews 107 2592-2614

Brigham DM 2013 Lanthanide-Polyaminopolycarboxylate Complexation Kinetics in High Lactate Media

Investigating the Aqueous Phase of TALSPEAK WASHINGTON STATE UNIVERSITY

Burns JR Ramshaw C 2001 The intensification of rapid reactions in multiphase systems using slug flow

in capillaries Lab Chip 1 10-15

Caldin E 2001 The mechanisms of fast reactions in solution IOS Press

Chinaud M Roumpea E-P Angeli P 2015 Studies of plug formation in microchannel liquidndashliquid flows

using advanced particle image velocimetry techniques Experimental Thermal and Fluid Science 69 99-110

17

Chun S Dzyuba SV Bartsch RA 2001 Influence of Structural Variation in Room-Temperature Ionic

Liquids on the Selectivity and Efficiency of Competitive Alkali Metal Salt Extraction by a Crown Ether Anal

Chem 73 3737-3741

De Morais C 2000 Recovery of europium and yttrium from color TV tubes 55 Congresso Anual

Associacao Brasileria de Metalurgia e Materiais Rio de Janeiro Brazil

Dehkordi AM 2001 Novel Type of Impinging Streams Contactor for LiquidminusLiquid Extraction Industrial

amp Engineering Chemistry Research 40 681-688

Dehkordi AM 2002 Liquid-liquid extraction with an interphase chemical reaction in an air-driven

two-impinging-streams reactors Effective interfacial area and overall mass-transfer coeffcient Ind

EngChem Res 41 4085-4093

Dessimoz A-L Cavin L Renken A Kiwi-Minsker L 2008 Liquidndashliquid two-phase flow patterns and

mass transfer characteristics in rectangular glass microreactors Chemical Engineering Science 63 4035-4044

Dore V Tsaoulidis D Angeli P 2012 Mixing patterns in water plugs during waterionic liquid segmented

flow in microchannels Chemical Engineering Science 80 334-341

Fernandes JB Sharma MM 1967 Effective interfacial area in agitated liquidmdashliquid contactors

Chemical Engineering Science 22 1267-1282

Ghaini A Kashid MN Agar DW 2010 Effective interfacial area for mass transfer in the liquidndashliquid

slug flow capillary microreactors Chemical Engineering and Processing Process Intensification 49 358-366

Goonan TG 2011 Rare Earth Elements--end Use and Recyclability US Department of the Interior US

Geological Survey

Horwitz EP Kalina DG Kaplan L Mason GW Diamond H 1982 Selected

Alkyl(phenyl)-NN-dialkylcarbamoylmethylphosphine Oxides as Extractants for Am(III) from Nitric Acid

Media Separation Science and Technology 17 1261-1279

Jovanović J Rebrov EV Nijhuis TA Kreutzer MT Hessel V Schouten JC 2012 LiquidndashLiquid

Flow in a Capillary Microreactor Hydrodynamic Flow Patterns and Extraction Performance Industrial amp

Engineering Chemistry Research 51 1015-1026

Kashid MN Gupta A Renken A Kiwi-Minsker L 2010 Numbering-up and mass transfer studies of

liquidndashliquid two-phase microstructured reactors Chemical Engineering Journal 158 233-240

Kashid MN IGerlach SGoetz JFranzke JFAcker FPlatte DWAgar STurek 2005 Internal

18

circulation within the liquid slugs of a liquidndashliquid slug-flow capillary microreactor IndustrialampEngineering

Chemistry Research 2005 5003-5010

Kashid MN Platte F Agar D Turek S 2007 Computational modelling of slug flow in a capillary

microreactor Journal of Computational and Applied Mathematics 203 487-497

Kececi S Woumlrner M Onea A Soyhan HS 2009 Recirculation time and liquid slug mass transfer in

co-current upward and downward Taylor flow Catalysis Today 147 S125-S131

Khakpay A Abolghasemi H Salimi-Khorshidi A 2009 The effects of a surfactant on mean drop size in a

mixer-settler extractor Chemical Engineering and Processing Process Intensification 48 1105-1111

Kiwi-Minsker L Renken A 2005 Microstructured reactors for catalytic reactions Catalysis Today 110

2-14

Kučera J Mizera J Řanda Z Vaacutevrovaacute M 2007 Pollution of agricultural crops with lanthanides thorium

and uranium studied by instrumental and radiochemical neutron activation analysis Journal of Radioanalytical

and Nuclear Chemistry 271 581-587

Lee C-J Yang B-R 1995 Extraction of trivalent europium via a supported liquid membrane containing

PC-88A as a mobile carrier The Chemical Engineering Journal and the Biochemical Engineering Journal 57

253-260

Lew K 2010 The 15 Lanthanides and the 15 Actinides The Rosen Publishing Group 30

Loumlwe H Ehrfeld W 1999 State-of-the-art in microreaction technology concepts manufacturing and

applications Electrochimica Acta 44 3679-3689

Matsumiya M Suda S Tsunashima K Sugiya M Kishioka S-y Matsuura H 2008 Electrochemical

behaviors of multivalent complexes in room temperature ionic liquids based on quaternary phosphonium

cations Journal of Electroanalytical Chemistry 622 129-135

Nakashima K Kubota F Maruyama T Goto M 2003 Ionic liquids as a novel solvent for lanthanide

extraction Analytical Sciences 19 1097-1098

Nakashima K Kubota F Maruyama T Goto M 2005 Feasibility of ionic liquids as alternative

separation media for industrial solvent extraction processes Industrial amp Engineering Chemistry Research 44

4368-4372

Okamura H Sakae H Kidani K Hirayama N Aoyagi N Saito T Shimojo K Naganawa H Imura

H 2012 Laser-induced fluorescence and infrared spectroscopic studies on the specific solvation of

19

tris(1-(2-thienyl)-444-trifluoro-13-butanedionato)europium(III) in an ionic liquid Polyhedron 31 748-753

Okubo Y Maki T Aoki N Hong Khoo T Ohmukai Y Mae K 2008 Liquidndashliquid extraction for

efficient synthesis and separation by utilizing micro spaces Chemical Engineering Science 63 4070-4077

Puranik S Sharma M 1970 Effective interfacial area in packed liquid extraction columns Chemical

Engineering Science 25 257-266

Rabah MA 2008 Recyclables recovery of europium and yttrium metals and some salts from spent

fluorescent lamps Waste management 28 318-325

Raimondi NDM Prat L Gourdon C Tasselli J 2014 Experiments of mass transfer with liquidndashliquid

slug flow in square microchannels Chemical Engineering Science 105 169-178

Rao CJ Venkatesan K Nagarajan K Srinivasan T Rao PV 2009 Electrochemical behavior of

europium (III) in N-butyl-N-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide Electrochimica Acta 54

4718-4725

Resende LV Morais CA 2010 Study of the recovery of rare earth elements from computer monitor scraps

ndash Leaching experiments Minerals Engineering 23 277-280

Ribeiro A Valente A Lobo V 2011 Diffusion behaviour of trivalent metal ions in aqueous solutions

Chemistry and Chemical Technology 5

Rout A Venkatesan KA Srinivasan TG Vasudeva Rao PR 2011a Extraction and third phase formation

behavior of Eu(III) IN CMPOndashTBP extractants present in room temperature ionic liquid Separation and

Purification Technology 76 238-243

Rout A Venkatesan KA Srinivasan TG Vasudeva Rao PR 2011b Room temperature ionic liquid

diluent for the extraction of Eu(III) using TRUEX extractants Journal of Radioanalytical and Nuclear

Chemistry 290 215-219

Rout A Venkatesan KA Srinivasan TG Vasudeva Rao PR 2012 Extraction behavior of actinides and

fission products in amide functionalized ionic liquid Separation and Purification Technology 97 164-171

Sarkar S Mumford CJ Phillips CR 1980 Liquid-Liquid Extraction with Interphase Chemical Reaction

in Agitated Columns 1 Mathematical Models Industrial amp Engineering Chemistry Process Design and

Development 19 665-671

Scheiff F Mendorf M Agar D Reis N Mackley M 2011 The separation of immiscible liquid slugs

within plastic microchannels using a metallic hydrophilic sidestream Lab Chip 11 1022-1029

20

Schulz W Horwitz E 1986 Recent progress in the extraction chemistry of actinide ions Journal of the Less

Common Metals 122 125-138

Sen N Darekar M Singh K Mukhopadhyay S Shenoy K Ghosh S 2014 Solvent extraction and

stripping studies in microchannels with TBP nitric acid system Solvent Extraction and Ion Exchange 32

281-300

Sengupta A Mohapatra PK Iqbal M Verboom W Huskens J Godbole SV 2012 Extraction of

Am(iii) using novel solvent systems containing a tripodal diglycolamide ligand in room temperature ionic

liquids a lsquogreenrsquo approach for radioactive waste processing RSC Advances 2 7492

Sukhamoy Sarkar JMumford C RPhillips C 1980 Liquid-liquid extraction with an interphase chemical

reaction in agitated columns1 Mathmatical models Industrialamp Engineering Chemistry Process Design and


Thulasidas T Abraham M Cerro R 1997 Flow patterns in liquid slugs during bubble-train flow inside

capillaries Chemical Engineering Science 52 2947-2962

Tsaoulidis D Angeli P 2015 Effect of channel size on liquid-liquid plug flow in small channels AIChE

Journal na-na

Tsaoulidis D Dore V Angeli P Plechkova NV Seddon KR 2013 Dioxouranium(VI) extraction in

microchannels using ionic liquids Chemical Engineering Journal 227 151-157

Tsoligkas AN Simmons MJH Wood J 2007 Influence of orientation upon the hydrodynamics of gasndash

liquid flow for square channels in monolith supports Chemical Engineering Science 62 4365-4378

Vandu CO Liu H Krishna R 2005 Mass transfer from Taylor bubbles rising in single capillaries


Verma R Sharma M 1975 Mass transfer in packed liquidmdashliquid extraction columns Chemical


Wang G Peng Q Li Y 2011 Lanthanide-doped nanocrystals synthesis optical-magnetic properties and

applications Accounts of chemical research 44 322-332

Kashid MN Harshe YM Agar DW2007 Liquid-liquid slug flow in capillary an alternative to suspended

drop or film contactors Industrial ampEngineering Chemistry Research 46 8420-8430

Kashid MN Renken A Kiwi-Minsker L 2011 Influence of flow regime on mass transfer in different

types of microchannels Industrial ampEngineering Chemistry Research 50 6906-6914

21

Xu B Cai W Liu X Zhang X 2013 Mass transfer behavior of liquidndashliquid slug flow in circular

cross-section microchannel Chemical Engineering Research and Design 91 1203-1211

Yang L Zhao Y Su Y Chen G 2013 An Experimental Study of Copper Extraction Characteristics in a

T-Junction Microchannel Chemical Engineering amp Technology 36 985-992

Yang X He L Qin S Tao G-H Huang M Lv Y 2014 Electrochemical and Thermodynamic

Properties of Ln(III) (Ln = Eu Sm Dy Nd) in 1-Butyl-3-Methylimidazolium Bromide Ionic Liquid PLoS

ONE 9 e95832

Yue J Luo L Gonthier Y Chen G Yuan Q 2009 An experimental study of airndashwater Taylor flow and

mass transfer inside square microchannels Chemical Engineering Science 64 3697-3708

22

Tables

Table 1

Properties of the test fluids

Propertyparameter (25ordmC) Fluidvalue

Density (ρ)[kgm3] Ionic liquid phase 1259

Aqueous phase 1030

Dynamic viscosity (μ)[cp] Ionic liquid phase 2559

Aqueous phase 075

Interfacial tension(γ)[mNm] Ionic liquid phase Aqueous phase =670

Eu(III) diffusion coefficient(D)[ m2 s-1] Ionic liquid phase 295times 10-12

Aqueous phase 786 times 10-8

Refractive index(n) Ionic liquid phase 1427

Aqueous phase 1339

FEP channel 134

Deionized water 1335

23

Table 2

Comparison of KLa values in liquid-liquid microfluidic systems using TY-junctions

Liquid-liquid

contactor

System KLa (s-1) α (m2 m-3) Reference

T-junction capillaries

ID=02 and 05mm

02M CMPO-12M

TBP[C4mim][NTf2]---1M

nitric acid

0005-005 3750-8250 Present work


ID= 05mm

50 TBP in cyclohexane---1M

nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm

Kerosenen-butanolwater 002-031 590-4800 Kashid et

al(2007)

Rectangular glass

microchannel 04mm

Hexane trichloroacetic acid

water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)

Capillary microreactor

ID=05mm

n-butyl formate-aqueous

NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)

Y-rectangular (015mm

ID) Concentric (glass

015mm)

Nonreacting water-acetone ndash

toluene

001-074 NA Kashid et al

(2011)

Opposed T-junction

ID=06 08 and 10mm

Sodium hydroxide---n-butyl

acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in

[C4mim][NTf2]---3M nitric

acid

0049-0312 NA Tsaoulidis et

al (2013)

T-junction PTFE

capillary with 2mm ID

00016 to 045ms

CuSO4H2SO4AD-100260 003-026 NA Yang et al

(2013)

24

T-junction serpentine

microchannel

ID=0278 and 0319

mm

30 TBP in dodecane (nitric

acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction

microchannel 210 μm

Wateracetonetoluene 161-844

6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25

Fig1 Sketch of the experimental set up including the high speed imaging system

26

Fig 2Top view sketch of the 02mm ID microchip

Fig 3 Chemical structure of the ionic liquid 1-butyl-3-methylimidazolium

bis[(trifluoromethyl)sulfonyl]amide ([C4min][NTf2])

27

Fig 4 Specific interfacial area against mixture velocity for different capillary diameters

Aqueous phase 1M nitric acid organic phase 02M CMPO-12M TBP[C4mim][NTf2]

28

Fig 5 Eu(III) distribution coefficients against initial nitric acid concentration at different initial Eu(III)

loading Aqueous phase 001-2M HNO3 organic phase 02M CMPO-12M TBP[C4mim][NTf2]

29

(a)Volumetric mass transfer coefficients

(b) Extraction efficiency

Fig 6 Variation of Eu(III) (a) extraction efficiency and (b) volumetric mass transfer coefficient with

residence time for different initial nitric acid concentrations Umix=05cms CL=5 15 25cm

30

Fig 7 Variation of Eu(III) volumetric mass transfer coefficient with mixture velocity for different initial

nitric acid concentrations CL=15cm 05mm ID

31

Fig 8 Variation of Eu(III) extraction efficiency with residence time for different initial nitric acid

concentrations CL=15cm 05mm ID

32

Fig 9 Variation of Eu(III) volumetric mass transfer coefficient with mixture velocity for different

capillary sizes 02mm and 05mm ID CL=25cm

33

(a) Averaged recirculation pattern

(b) Averaged recirculation time

Fig10 (a) Averaged recirculation pattern and (b) averaged recirculation time profile along an aqueous

plug 05mm ID channel Qaq=QIL=3534mlh

34

Fig 11 Recirculation time and mass transfer coefficient as a function of plug travel time

Aqueous phase 1M nitric acid organic phase 02M CMPO-12M TBP[C4mim][NTf2] CL=15cm

05mm ID Qaq=QIL

35

Fig 12 Comparison of experimental KLa values against predicted ones

(System 1M nitric acid-02M CMPO-12M TBP[C4mim][NTf2] Qaq=QIL ID=02 and 05 mm capillary)

2

Assmann et al 2013 Xu et al 2013 Yang et al 2013)As extraction efficiencies depend on

concentration gradients interfacial area and residence times (Okubo et al 2008) the exact flow pattern

within the separation unit becomes important Plug (or segmented) flow in particular where one phase

forms dispersed plugs with diameter larger than the channel size separated by continuous phase slugs is a

preferred pattern because the circulation patterns forming in the two phases and the thin films separating

the plugs from the channel wall enhance mass transfer (Burns and Ramshaw 2001 Kashid et al 2005

Okubo et al 2008 Jovanović et al 2012) In addition the dispersed plug sizes are very regular and can

be controlled via the choice of the inlet geometry which further reduces non-uniformities common in

large scale extraction units such as mixers-settlers(Khakpay et al 2009) Knowledge of the interfacial

area is very important in the understanding and modelling of extraction operations Chemical reactions

eg alkaline hydrolysis of esters have been used to obtain global values of interfacial area in units such

as agitated contactors(Fernandes and Sharma 1967) packed columns(Puranik and Sharma 1970 Verma

and Sharma 1975)and two-impinging-stream reactors(Dehkordi 2002)In small channels where flow

patterns are well defined high speed imaging can be used to acquire details of the flow pattern locally

such as film thickness and plug length and estimate the interfacial area (Ghaini et al 2010 Xu et al

2013)

One of the separations that can benefit from operation in small channels is the extraction of lanthanides

from acidic solutions Lanthanides with their strong photoluminescence and magnetic properties are

important to many industrial applications Europium and yttrium oxides can be used as fluorescing agents

for anodic rays in television and monitor screens (Lee and Yang 1995) Lanthanide oxides are used to

colour ceramics and glasses (Goonan 2011) Some compounds of lanthanides find applications as

catalysts for example oxides of thorium and cerium are used in the conversion of crude oil into common

consumer products (Lew 2010) Lanthanides have also been used to regulate nuclear reactors as control

rods because they absorb neutrons (Kučera et al 2007) and to make strong permanent magnets (Wang et

al 2011) Scarcity on natural resources means that the large quantities of lanthanides present in

electronic waste such as spent fluorescent lamps (Rabah 2008) computer monitor scraps (Resende and

Morais 2010) and colour TV tubes (De Morais 2000) need to be recycled In the field of spent nuclear

fuel reprocessing recovery of the trivalent actinides and lanthanides is a key step in high-level waste

management Since trivalent lanthanides cannot be extracted by TBP they are rejected to high-level

liquid waste in the PUREX process (Rout et al 2011a) They can however be extracted by the TRUEX

solvent which is a mixture of 02 M CMOP- 12 M TBP in n-dodecane (Horwitz et al 1982 Schulz and

Horwitz 1986)

3

































4

































5



























(1)








6



+ 3C4mim+ (2)

















2014)

120572119901 =4119882119901(119871119875minus119908119901)+120587119882119901

2

1198711198801198621198681198632 (3)










7





mass transfer





119863119864119906 =119862119886119902119894119899119894minus119862119886119902

119890

119862119886119902119890 (4)






















8

al 2011a)





∆119871119872119862119863=(119862119886119902119894119899119894


ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)


119873 = 119870119871∆119871119872119862119863 (6)


=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)



119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)


amount transferable



119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)












9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



3

































4

































5



























(1)








6



+ 3C4mim+ (2)

















2014)

120572119901 =4119882119901(119871119875minus119908119901)+120587119882119901

2

1198711198801198621198681198632 (3)










7





mass transfer





119863119864119906 =119862119886119902119894119899119894minus119862119886119902

119890

119862119886119902119890 (4)






















8

al 2011a)





∆119871119872119862119863=(119862119886119902119894119899119894


ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)


119873 = 119870119871∆119871119872119862119863 (6)


=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)



119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)


amount transferable



119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)












9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



4

































5



























(1)








6



+ 3C4mim+ (2)

















2014)

120572119901 =4119882119901(119871119875minus119908119901)+120587119882119901

2

1198711198801198621198681198632 (3)










7





mass transfer





119863119864119906 =119862119886119902119894119899119894minus119862119886119902

119890

119862119886119902119890 (4)






















8

al 2011a)





∆119871119872119862119863=(119862119886119902119894119899119894


ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)


119873 = 119870119871∆119871119872119862119863 (6)


=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)



119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)


amount transferable



119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)












9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



5



























(1)








6



+ 3C4mim+ (2)

















2014)

120572119901 =4119882119901(119871119875minus119908119901)+120587119882119901

2

1198711198801198621198681198632 (3)










7





mass transfer





119863119864119906 =119862119886119902119894119899119894minus119862119886119902

119890

119862119886119902119890 (4)






















8

al 2011a)





∆119871119872119862119863=(119862119886119902119894119899119894


ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)


119873 = 119870119871∆119871119872119862119863 (6)


=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)



119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)


amount transferable



119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)












9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



6



+ 3C4mim+ (2)

















2014)

120572119901 =4119882119901(119871119875minus119908119901)+120587119882119901

2

1198711198801198621198681198632 (3)










7





mass transfer





119863119864119906 =119862119886119902119894119899119894minus119862119886119902

119890

119862119886119902119890 (4)






















8

al 2011a)





∆119871119872119862119863=(119862119886119902119894119899119894


ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)


119873 = 119870119871∆119871119872119862119863 (6)


=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)



119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)


amount transferable



119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)












9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



7





mass transfer





119863119864119906 =119862119886119902119894119899119894minus119862119886119902

119890

119862119886119902119890 (4)






















8

al 2011a)





∆119871119872119862119863=(119862119886119902119894119899119894


ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)


119873 = 119870119871∆119871119872119862119863 (6)


=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)



119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)


amount transferable



119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)












9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



8

al 2011a)





∆119871119872119862119863=(119862119886119902119894119899119894


ln(119862119886119902119894119899119894119890 minus 119862119886119902119894119899)(119862119886119902119891119894119899

119890 minus 119862119886119902119891119894119899)(5)


119873 = 119870119871∆119871119872119862119863 (6)


=119928119938119954(119914119938119954119943119946119951minus119914119938119954119946119951)

119933120630119953(7)



119870119871120572 =1

(1+1

119863119864119906

119876119886119902

119876119900119903119892)120591

ln (119862119886119902119891119894119899minus119862119886119902

119890

119862119886119902119894119899minus119862119886119902119890 ) (8)


amount transferable



119862119886119902119894119899minus119862119886119902119891119894119899

119862119886119902119894119899minus119862119886119902119890 (9)












9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



9








equilibrium value





















119870119871119888119886119901 = 2radic2

120587radic

119863119880119875

119889119888 (10)

119870119871119891119894119897119898 = 2radic119863

120587119905119891119894119897119898

119897119899(1 ∆frasl )


10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



10

119870119871119891119894119897119898 = 341119863


119870119871120572 = 119870119871119888119886119901120572119888119886119901 + 119870119871119891119894119897119898120572119891119894119897119898 (13)






























11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



11





















τ(x) =Lpy0

int u(xy)dyy0

0

congLPy0

∆ sum ui|xi=Ni=1

(14)











12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



12





























119896119871120572 = 0111(119880119901+119880119904)

119


119896119871120572 = 365radic119863119880119901

119871119880119862

1

119868119863 (16 Vandu et al 2005)

119896119871119886 =167

119868119863(

119880119901

119868119863)

05

(119871119901

119868119863)

015

(119871119901+119871119878

119868119863)

005

(17 Yue et al 2009)

13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



13

119896119871120572119871119901

119906119898119894119909= 00257119862119886minus06119877119890005 (

119868119863

119871119901)

minus01

































14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



14





4 Conclusions





















Nomenclature

Latin Symbols




15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



15












Lfilm film length m


Ls slug length m









120588119880119898119894119909119868119863







Greek Symbols


ρ density kgm-3

τ residence time s






16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



16

Acknowledgements





high-speed camera

References












Exchange 29 577-601









17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



17



Chem 73 3737-3741

















Geological Survey










18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



18










2-14






253-260











4368-4372



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



19












4718-4725


















20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



20





281-300










Journal na-na















21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



21







ONE 9 e95832



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



22

Tables

Table 1




Aqueous phase 1030


Aqueous phase 075





Aqueous phase 1339

FEP channel 134


23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



23

Table 2


Liquid-liquid

contactor



ID=02 and 05mm

02M CMPO-12M


nitric acid

0005-005 3750-8250 Present work


ID= 05mm


nitric acid

00262-00643 3613-3979 Present work

Soda-lime glass

038mm depth chip

Keroseneacetic acid

water+NaOH

Order of

magnitude of

05

NA Burns and

Ramshaw

(2001)

PTFE capillary with

Y-junction 05 075

and 1mm


al(2007)

Rectangular glass

microchannel 04mm


water+NaOH

02-05 10700-112

00

Dessimoz et

al (2008)


ID=05mm


NaOH solution

090-167 1600-3200 Ghaini et al

(2010)

Square (glass 04mm)

T-square (glass

04mm) T-trapezoidal

0269mm)



015mm)


toluene


(2011)

Opposed T-junction

ID=06 08 and 10mm


acetate

0006-037 1300-4100 Xu et al

(2013)

T-junction Teflon

channel ID=05mm

30TBP in


acid


al (2013)

T-junction PTFE


00016 to 045ms


(2013)

24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



24


microchannel

ID=0278 and 0319

mm


acid)--- water

0001-4 NA Sen et al

(2014)

Square Glass

T-junction



6090-1340

0

Raimondi et

al (2014)

Packed extraction

columns


NaOH solution

00034-0005 80-450 Verma and

Sharma

(1975)

RTL extractors

(Graesser raining

bucket)


NaOH solution

(06-13)times10-6 90-140 Alper (1988)

25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



25


26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



26




27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



27



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



28



29





30



31



32



33





34



05mm ID Qaq=QIL

35



29





30



31



32



33





34



05mm ID Qaq=QIL

35



30



31



32



33





34



05mm ID Qaq=QIL

35



31



32



33





34



05mm ID Qaq=QIL

35



32



33





34



05mm ID Qaq=QIL

35



33





34



05mm ID Qaq=QIL

35



34



05mm ID Qaq=QIL

35



35



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